Easiest to find or to do? To find would be in through County or Wretched Rabbit, through to Stop Pot, up the iron ladder and turn R at Main Line Terminus. To do - probably Manc Bypass.
From the "other" end, Cow Pot's direct route drops you into Fall Pot (luvverly pitch), thence down into the Main Drain, upstream to Oxbow corner, up into high level stuff and you're not far away. Sorry to say it but "it all depends" - which end of the system do you know?